<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <title>Example</title>
</head>

<body>
  <p id="status">Ready</p>
  <button id="send">Send Message</button>
  <p>
    <iframe name="nested" src="otherdomain.html" width="90%" height="75px"></iframe>
  </p>

  <script type="text/javascript">
    document.getElementById('send').onclick = function() {
      document.getElementById('status').innerHTML = "Message Sent";
    }
  </script>
</body>

</html>
